I've got this in my /var/log/mail.info. Can anyone decypher any of the following(?):

Feb 26 11:43:26 STINTR01 postfix/pickup[10519]: CE90B1A83B6: uid=33 from=<webmaster@<domain.com>>
Feb 26 11:43:26 STINTR01 postfix/cleanup[10586]: CE90B1A83B6: message-id=<20090226114326.CE90B1A83B6@localhost>
Feb 26 11:43:26 STINTR01 postfix/qmgr[10520]: CE90B1A83B6: from=<webmaster@<domain.com>>, size=383, nrcpt=1 (queue active)
Feb 26 11:43:26 STINTR01 postfix/smtp[10588]: CE90B1A83B6: to=<WebTeam@<domain.com>>, relay=none, delay=0.06, delays=0.05/0/0/0, dsn=5.4.4, status=bounced (Host or domain name not found. Name service error for name=<domain.com> type=AAAA: Host found but no data record of requested type)
Feb 26 11:43:26 STINTR01 postfix/cleanup[10586]: E0A181A83BA: message-id=<20090226114326.E0A181A83BA@localhost>
Feb 26 11:43:26 STINTR01 postfix/bounce[10589]: CE90B1A83B6: sender non-delivery notification: E0A181A83BA
Feb 26 11:43:26 STINTR01 postfix/qmgr[10520]: E0A181A83BA: from=<>, size=2273, nrcpt=1 (queue active)
Feb 26 11:43:26 STINTR01 postfix/qmgr[10520]: CE90B1A83B6: removed
Feb 26 11:43:26 STINTR01 postfix/smtp[10588]: E0A181A83BA: to=<webmaster@<domain.com>>, relay=none, delay=0.03, delays=0.03/0/0/0, dsn=5.4.4, status=bounced (Host or domain name not found. Name service error for name=<domain.com> type=AAAA: Host found but no data record of requested type)
Feb 26 11:43:26 STINTR01 postfix/qmgr[10520]: E0A181A83BA: removed

Have you done what I suggested in post 9 and added a line to your hosts file?

Try "nslookup <domain.com>"

from your server.

I did. No joy. What worked was just specifying the relayhost in /etc/postfix/main.cf to an IP address of a different (external) SMTP server.

Really wish I could got Ubuntu to serve as an smtp server.

Sounds like your problem is name resolution - nothing to do with postfix

I've done what you suggested in post 9. I'm afraid it didn't work :(

Can you show the output of

nslookup domain.com

cat /etc/hosts

cat /etc/host.conf